1. Field of the Invention
The present invention relates to a communication control system, a communication control method and a computer-readable storage medium for storing a program for ensuring communication quality.
2. Description of the Related Art
Conventionally, control techniques in the case where communication bandwidth required by communication terminals varies include the following.
In a first technique, the sequence of video frames (e.g., I frames, P frames and B frames in an MPEG video sequence) is monitored at a higher layer than the MAC layer. The size of video frames and the pattern of video frames per unit of time are determined, and a future data rate at a future time is predicted based on the size of video frames and the pattern of video frames per unit of time. Parameters (e.g., AIFS, CW, CWmax, CWmin) of the MAC layer are then adjusted based on the predicted future data rate at the future time (e.g., see Japanese Patent Laid-Open No. 2007-251940).
In a second technique, a QoS management unit is provided in a base station in a wireless communication system in which a plurality of terminals 1 to n communicates information with a common base station via a wireless transmission channel. If a change in transmission speed is detected by a link adaptation controller, the QoS management unit is notified. Scheduling and rescheduling of bandwidth allocation to the terminals 1 to n by the QoS management unit are triggered by a change in transmission speed due to link adaptation (e.g., see Japanese Patent Laid-Open No. 2005-277862).
However, the first technique is an operation for individual terminals, and does not touch on control in the case of a plurality of terminals.
Also, the second technique only deals with a change in the state of a link, and does not take into account the data amount required by applications.
Also, investigations were conducted into whether a wired communication technique can be applied to this problem. In the case of wired communication, the influence of other terminals can be physically blocked by a switching HUB or the like. Also, in the case of sharing media, conflicts can nearly always be detected. In other words, a change in the state of communication media differs in nature from the case of wireless. Therefore, a conventional wired communication technique cannot be directly applied to retaining quality and ensuring bandwidth with wireless.